The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to computer interface devices that allow the user to provide input to computer systems and allow computer systems to provide force feedback to the user.
A computer system in typical usage by a user displays a visual environment on a display output device. Using an interface device, the user can interact with the displayed environment to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), etc. Common human-computer interface devices used for such interaction include a joystick, mouse, trackball, steering wheel, stylus, tablet, pressure-sensitive sphere, or the like, that is connected to the computer system controlling the displayed environment. Typically, the computer updates the environment in response to the user""s manipulation of a user-manipulatable physical object such as a joystick handle or mouse, and provides visual and audio feedback to the user utilizing the display screen and audio speakers. The computer senses the user""s manipulation of the user object through sensors provided on the interface device that send locative signals to the computer. For example, the computer displays a cursor or other graphical object in a graphical environment, where the location of the cursor is responsive to the motion of the user object.
In some interface devices, tactile and/or haptic feedback is also provided to the user, more generally known as xe2x80x9cforce feedback.xe2x80x9d These types of interface devices can provide physical sensations which are felt by the user manipulating a user manipulatable object of the interface device. For example, the Force-FX joystick controller from CH Products, Inc. and Immersion Corporation may be connected to a computer and provides forces in the degrees of freedom of motion of the joystick to a user of the controller. One or more motors or other actuators are coupled to the joystick and are connected to the controlling computer system. The computer system controls forces on the joystick in conjunction and coordinated with displayed events and interactions by sending control signals or commands to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the joystick or other object of the interface device. For example, when the user moves the manipulatable object and causes a displayed cursor to interact with a different displayed graphical object, the computer can issue a command that causes the actuator to output a force on the user object, conveying a feel sensation to the user. Other force feedback controllers include a force feedback mouse that provides forces in the degrees of freedom of motion of the mouse, and a steering wheel controller outputting forces in the rotary degree of freedom of the wheel.
One problem with current force feedback controllers in the home consumer market is the high manufacturing cost of such devices, which makes the devices expensive for the consumer. A large part of this manufacturing expense is due to the inclusion of multiple actuators and corresponding control electronics in the force feedback device. In addition, high quality transmission components such as linkages and bearings must be provided to accurately transmit forces from the actuators to the user manipulandum and to allow accurate sensing of the motion of the user object. These components are complex and require greater precision in their manufacture than many of the other components in an interface device, and thus further add to the cost of the device. A need therefore exists for a force feedback device that is lower in cost to manufacture yet offers the user force feedback to enhance the interaction with a computer application.
The present invention is directed to a low-cost force feedback interface which provides a linear actuator along a non-primary axis or degree of freedom. This configuration can provide a simpler, lower cost force feedback device, especially when motion in the non-primary axis is not sensed and no other actuators are used.
More specifically, the present invention relates to a force feedback interface device that is coupled to a host computer system which implements a host application program. The interface device includes a user manipulatable object, such as a mouse or joystick, contacted by a user and movable in physical space in at least one primary degree of freedom. At least one sensor detects the movement of the user object in the degree of freedom and outputs sensor signals representative of the movement. An actuator is coupled to the user manipulatable object and applies a linear output force along a non-primary axis extending through the user manipulatable object, where the force is output in a degree of freedom not sensed by the sensor. Preferably, there are no other actuators in the device. Force sensations such as a jolt, vibration, a constant force, and a texture force can be output on the user object with the actuator.
In preferred embodiments, the actuator outputs the force directly on the user manipulatable object, such that no transmission system is required to be provided between the actuator and the user manipulatable object, thus greatly reducing the cost of the device. In addition, the actuator can include a physical spring or other spring device for biasing said at least a portion of the user manipulatable object toward an extended position. The actuator can take a variety of forms, such as a linear voice coil actuator, a linear solenoid, or a voice magnet. A microprocessor local to the interface device can be provided to receive host commands from the host computer and output force signals to the actuator for controlling the output force on the user object. The microprocessor can receive sensor signals from the sensors and report locative data to the host computer indicative of the movement of the user object. Alternatively, a sensor can be coupled to the actuator to determine a position of the user manipulatable object in the degree of freedom of the actuator.
In one embodiment in which the user manipulatable object is moved in a planar degree of freedom, the output force of the actuator can be provided in a direction approximately perpendicular to the plane of motion. For example, in a mouse embodiment, the force is applied about perpendicularly to the planar mouse workspace and is applied to an entire portion of the mouse that is grasped or rested upon by the user""s hand. In a particular mouse embodiment, the actuator is coupled to a housing of the mouse and moves a portion of the housing in the perpendicular direction. Such a moveable portion of the housing can be a cover portion of the housing that is movably coupled to a base portion of the housing, for example by a hinge, where the cover portion is moved by the actuator with respect to the base portion. The output force can be correlated with a graphical representation displayed by the host computer, where a position of the mouse in the planar workspace corresponds with a position of a cursor displayed in the graphical representation. For example, a jolt force can be output when the mouse crosses a boundary of a window or icon. Or, the output force can be correlated with an elevation of a portion of a 3-D graphical representation having different elevations on which the cursor is displayed. In a different embodiment, the user manipulatable object can be a stylus; or a wheel, such as a steering wheel, that rotates in the single plane, and where the axis extends approximately through a center of the wheel.
In a different embodiment, the user manipulatable object is moved in two sensed rotary degrees of freedom with respect to a ground, where the degrees of freedom approximately define a portion of a surface of a sphere. For example, the user manipulatable object can be at least a portion of a joystick handle that is typically moved in such rotary degrees of freedom. The actuator of the device applies an output force in a linear degree of freedom that is approximately radial to the sphere, where preferably no force is output in the two primary sensed degrees of freedom. The force is applied along a lengthwise axis of the user manipulatable object.
In another embodiment, the user manipulatable object is movable in physical space in a plurality of degrees of freedom with respect to a ground, and a linear actuator applies a linear output force only along a lengthwise axis of the user manipulatable object and not in the plurality of degrees of freedom. One such embodiment provides a stylus as a user manipulatable object, where the sensor can be included in a tablet which is contacted by the stylus. In one embodiment, the stylus includes a rigid tip for contact with the tablet, where the actuator outputs a force to move a body portion of the stylus relative to a tip portion of the stylus. In a different stylus embodiment, the stylus includes a ball in a tip of the stylus, where the ball rotates in place when the stylus is moved across a surface. The actuator can force a brake pad against the ball to output a resistive force on the stylus.
The present invention advantageously provides a force feedback device that is significantly lower in cost than other types of force feedback devices and is thus quite suitable for home consumer applications. A single actuator can be provided that directly applies force to the user manipulatable object, thus saving cost by the elimination of multiple actuators and complex force transmission and control systems. The actuator does not output force in a main sensed degree of freedom of the device, thus allowing sensors to read the position of the user object without substantial interference from forces and also simplifying the control of output forces. Furthermore, the actuator of the present invention can provide a variety of different types of force sensations to enhance the user""s experience and interface with a computer application.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.